Non-reinforced coated substrates may be manufactured by a number of methods, as described with reference to FIGS. 1-10 and in the accompanying text. The methods and systems associated with the manufacture of non-reinforced coated substrates are also described in U.S. Pat. No. 5,192,586 to Mertinooke et al., the disclosure of which and all references of record therein and in the reexamination proceeding thereof are incorporated by reference herein in their entireties.
In many applications, it is desirable to provide a relatively thin, outer layer or skin for a substrate, which may be a rigid or non-rigid foam profile or other material. The substrate may include a plurality of components, some rigid and some nonrigid. The layer or skin may perform a variety of functions, such as protecting the substrate from adverse external conditions, providing the external surface of the substrate or portions thereof with characteristics suitable for particular applications, providing an aesthetically appealing finished product, and the like. The outer layer or skin may also improve the tear resistance of the substrate and enhance overall strength providing a more durable and rugged finished product. A conducting wire surrounded by an insulating layer is one example of a substrate having an outer layer performing such functions. One such substrate which may include an outer layer or skin is a weatherseal or weatherstrip, embodiments of which are described herein, however, the method and apparatus described herein are not limited in this respect; indeed, it is broadly applicable where it is desired to provide an outer layer or skin for rigid and non-rigid substrates including, but not limited to, foams, metals, and previously extruded plastics.
In general, weatherseals seal joints or spaces around doors and windows so as to inhibit infiltration of air, rain, snow, and other elements. Effective weatherseals can reduce both heating costs in winter and cooling costs in summer. Certain characteristics are desirable to produce an effective weatherseal. First, a weatherseal should have good compression set resistance. Compression set resistance refers to the ability of a material to resume its initial shape after being subjected to a compressive load. Failure to resume this initial shape may result in an uneven seal and reduce the effectiveness of the weatherseal. Second, a weatherseal should be soft and yielding, i.e., it should be easily compressible and conform to irregular surfaces. The gaps in doors, windows and the like in which weatherseals are utilized differ in size due to construction and other factors, and a weatherseal should have sufficient compressibility to conform to a wide range of gap sizes. Compressibility also ensures that a door or window, for example, can be closed without excessive force and still compress the weatherseal sufficiently to form the necessary seal.
The prior art discloses many materials which are utilized as weatherseals. U.S. Pat. Nos. 4,328,273 and 4,185,416 disclose the use of urethane foams for a weatherseal. Commonly assigned U.S. Pat. Nos. 4,898,760, 5,192,586, 5,393,796, 5,512,601, 5,607,629, 5,654,346, 5,728,406, and 5,788,889, the disclosures of which are incorporated herein by reference in their entireties, disclose the use of a low density foamed thermoplastic elastomer for a weatherseal. However, these and similar materials may have relatively high coefficients of friction and may be easily damaged. Thus, their effectiveness and utility as a weatherseal may be reduced. These problems are magnified where the weatherseal is subjected to sliding contact or other abrasive forces; thus, a method of manufacturing a weatherstrip having reduced frictional characteristics when sliding against a surface is desirable.
In order to alleviate the problems described above, an outer layer or skin is typically provided for the weatherseal. The outer layer generally has a low coefficient of friction relative to the surface of contact to facilitate relative motion and may be generally flexible to permit compression of the underlying seal. The outer layer also protects the seal from rips and tears caused by sliding contact or other abrasive forces. Low friction materials such as polyethylene copolymers, polyvinylchloride, and polypropylene copolymers have been utilized in the prior art for this outer layer.
There are several disadvantages, however, associated with providing these low friction outer layers. Attaching the outer layer to the underlying seal may require a separate manufacturing step and increase the labor and associated costs required to make the seal. If the outer layer is applied as a crosshead extrusion to the weatherseal, orientation of the outer layer during “draw-down” onto the seal creates low resistance to tears along the length of the seal. Thus, an initially small tear in the outer layer can propagate into a much larger tear, adversely affecting the effectiveness and utility of the weatherseal. Additionally, crosshead extrusion apparatus generally requires complex arrangements of equipment and expensive dies. These factors also increase production costs.
One prior art technique provides an outer skin for a substrate by melting a resin and placing the melted resin in a tank or pool with an entrance opening and an exit opening. The substrate is then pulled or dragged through the melted resin. The exit opening serves as a doctor blade to configure the outer layer. However, it is difficult to precisely control the thickness of the outer layer or to selectively coat portions of the substrate utilizing this prior art technique. Also, it is difficult to provide an outer layer of varying thickness. Finally, the pressure and drag exerted on a non-rigid substrate such as a foam by a viscous melted resin deforms and stretches the non-rigid substrate and generates a low quality product.